Over the past few years, products such as games consoles and more recently the mobile phone have introduced gesture control to a consumer audience. For example, gesture control can be used to turn a device on and off using a hand gesture, or to control a character in a video game based on a user's own bodily motion.
Gesture control is based on gesture recognition, which can be implemented using one or a combination of various technologies. One such technology is depth-aware image sensing, which is able to produce a 3D image based on time-of-flight information. For example a 3D camera will not only capture visible light over a two-dimensional pixel array, but will also augment this with time-of-flight information for the light received at some or all of the pixels. Another possibility is to use an image recognition algorithm to recognise a gesture in an image captured from a conventional 2D camera. Yet another possibility is to detect motion based on one or more accelerometers and/or rotational sensors such as gyroscopes or magnetometers disposed about a user's person, whether being worn or held by the user.
A gesture is an action performed explicitly by a human user for the purpose of signalling an intention to control some system or apparatus. Further, the term “gesture” as used herein refers to motion of at least one bodily member through the air (or other fluid medium of the space the user is occupying, e.g. water). As such it excludes an action detected purely by detecting the bodily member in question being pressed or held against a button or a control surface such as a touch screen, pressure pad or track pad (whether directly or indirectly via an implement such as a stylus). It also excludes detection purely based on moving a sensing device over a surface while in contact with that surface, e.g. a mouse. Rather, detecting a gesture means detecting the motion of the user by means of a contactless or non-tactile sensing principle. In the case of two- or three-dimensional image recognition, the detection may be achieved without the user necessarily needing to touch any controller device at all. In the case of a sensor or sensors disposed about the user's person, e.g. one or more accelerometers worn on a wristband or carried as part of handheld controller, the user does touch the device housing the sensor(s) but the sensing mechanism itself is based on a non-tactile principle in that the device and sensor move with the gesture formed by the user's bodily member, e.g. as is the case with a gesture-based games controller. This may be contrasted with a tactile principle of sensing whereby the action is detected by the bodily member or implement moving over the sensor surface while in contact, and/or being pressed against the sensor while the device housing it remains still or is braced to resist that pressure, as is the case with pressing a button or operating a touch screen.
One application of gesture control is to control the lighting in a space such as a room. US2012/0019168 discloses embodiments of a system in which lighting is controlled either based on gestures or other types of action. According to US'168, an image from a camera is analysed to determine a type of action being performed by a user, and also to determine the coordinates of the user within a room. In one embodiment of US'168, the detected action is not an explicit gesture but rather whether the user is walking, reading, writing or operating a personal computer. In this embodiment the lights are turned on only in a zone where the user is detected, or the lights are turned on in a distribution around the user such that the brightness of the different lights decreases with their distance from the user's detected coordinates. The brightness in the zone or overall brightness of the distribution depends on the type of action, e.g. whether walking or sitting at a PC. In another embodiment of US'168, the system does work based on gesture control: the user raises his or her hand to turn the lights on, and lowers the hand to turn the lights off. In this embodiment the detected coordinates of the user are used as “marker information” to aid the system in learning the gesture.